rcmgr: centralize blocked resource logging through trace reporter

[sneaxhuh]

Fixes #1744

This change consolidates debug logging for blocked resources into a centralized trace reporter system. Previously, debug logs for blocked resources were scattered throughout the codebase and didn't always align with the metrics, which were reliably tracked through trace events.

Changes:

• Add LogReporter that consumes trace events and logs blocked resources
• Remove ad-hoc log.Debug() calls from scope.go
• Install LogReporter by default in NewResourceManager
• Add tests for LogReporter functionality

Benefits:

• Logs and metrics now use the same source (trace events)
• More maintainable centralized logging approach
• Consistent blocked resource reporting